I would be wary of whistleblowing, but I would also be very wary of saying anything more to your employer than what is legally required (or than your lawyer advises). I don't see that we have socially made whistleblowing worth the risk to you, therefore, you should not take that risk, but if it helps your case, your severance, whatever, for your soon-to-be-former employer think that you might make trouble for them if they piss you off even more, that might be okay (if they're certain that you might make trouble for them, that's another matter and maybe a problem).
For the non-legal and probably more useful advice, this does not sound like a job that is worth keeping. You can't fix a bad boss, you're not paid enough to fix a bad boss (it ought to be the case that you would get a massive bonus for fixing a bad boss, but sadly the world does not work that way) better to look out for your own sanity and well-being. Don't burn bridges, don't slack off, I also don't recommend knocking yourself out in an attempt to save your job because (you wrote here for advice, here it is) it's not worth saving, DO prepare a resume and send it out, and follow the usual recipe of applying to as many places as you can stand managing all at once. It ought to take a few weeks for the sent resumes to turn into interviews, so it's not that likely to take too much of your (not-slacking-off) time. Ask your lawyer exactly what to say if a potential employer asks why you're leaving, because it's a delicate dance and there's things you probably cannot safely say (for example, what you've said here...).
However, there are not many actions in business that are perfectly ethical.
And, you won't always have decent recourse in law even if someone acts illegally against you.
For now, good luck.
I would also like to ensure that I correct the original comment in that I do not have sufficient legal knowledge to be certain that anything illegal or improper was done, which is why I am consulting with counsel before acting.